如何模拟设置一个方法以返回不同的值

Question

下面是我试图为CallMethod 编写单元测试用例的代码

public async Task<String> CallMethod(string accountName)
{
var response= await GetResponseAsync(Name);
var finalresponse= await PostReponseAsync(response);
return finalresponse;
}

private async Task GetResponseAsync(string Name)
{
var param = Name;
using (var httpClient = _httpClientFactory.CreateClient())
{
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "token");
var response = await httpClient.GetAsync(URL +"?" + param);
if (response != null)
{
var responseMessage = await response.Content.ReadAsStringAsync();
}
}
}

private async Task PostReponseAsync(string reponse)
{
var json = JsonConvert.SerializeObject(reponse);
var data = new StringContent(json, Encoding.UTF8, "application/json");
using (var httpClient = _httpClientFactory.CreateClient())
{
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", "token");
var response = await httpClient.PostAsync(URl, data);
if (response != null)
{
var responseMessage = await response.Content.ReadAsStringAsync();
}
}
}

单元测试方法：

[TestMethod]
public async Task CallMethod()
{
// Arrange
string Name = "Value";

var GetResponseMessage = new HttpResponseMessage
{
StatusCode = HttpStatusCode.OK,
Content = new StringContent("Message1"),
};

var postResponseMessage = new HttpResponseMessage
{
StatusCode = HttpStatusCode.OK,
Content = new StringContent("Message2"),
};
var handlerMock = new Mock<HttpMessageHandler>();
handlerMock.Protected().SetupSequence<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>()).ReturnsAsync(GetResponseMessage).ReturnsAsync(postResponseMessage);
var httpClient = new HttpClient(handlerMock.Object);
_mockHttpClientFactory.Setup(_ => _.CreateClient(It.IsAny<string>())).Returns(httpClient);
// Act
var response = await class.CallMethod( accountName);
// Assert            
}

对于GetResponseAsync方法，我正在获取响应，但当PostReponseAsync方法调用它时，会抛出异常，如下所示

Project.CallMethod引发异常：System.ObjectDisposedException：无法访问已释放的对象。对象名称：'System.Net.Http.HttpClient

有人能帮我吗。

Answer 1

Mock将客户端与工厂分离，因为每个方法都会处理它使用的客户端。

[TestMethod]
public async Task CallMethod() {
// Arrange
string Name = "Value";

var GetResponseMessage = new HttpResponseMessage {
StatusCode = HttpStatusCode.OK,
Content = new StringContent("Message1"),
};
var getHandlerMock = new Mock<HttpMessageHandler>();
getHandlerMock.Protected()
.Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
.ReturnsAsync(GetResponseMessage);
var postResponseMessage = new HttpResponseMessage {
StatusCode = HttpStatusCode.OK,
Content = new StringContent("Message2"),
};
var postHandlerMock = new Mock<HttpMessageHandler>();
postHandlerMock.Protected()
.Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
.ReturnsAsync(postResponseMessage);
var getHttpClient = new HttpClient(getHandlerMock.Object);
var postHttpClient = new HttpClient(postHandlerMock.Object);
_mockHttpClientFactory
.SetupSequence(_ => _.CreateClient(It.IsAny<string>()))
.Returns(getHttpClient)
.Returns(postHttpClient);
// Act
var response = await class.CallMethod(accountName);
// Assert
//...      
}